Prominent Enhancement of Nonlinear Optical Absorption in SnS₂ Nanosheets through Controllable Electrodeposition of Porphyrins

Abstract

Constructing organic-inorganic composites presents a promising approach to enhance the nonlinear optical (NLO) response of materials. However, the effectiveness of this approach is impeded by the complexity of synthesis procedures and challenges in controlling the loading amount. Herein, a convenient and controllable electrodeposition method to non-covalently combine SnS2 with tetracationic porphyrin (TMPyP) and the remarkable enhancement in NLO absorption of the resultant composite, are introduced. Through this method, a series of SnS2/TMPyP thin films are synthesized, allowing for the regulation of porphyrin loading via varying the deposition time. These resultant SnS2/TMPyP composites exhibit prominent nonlinear absorption coefficients when subjected to femtosecond laser irradiation of varying wavelengths. Notably, the compound with an electrochemical deposition time of 30 s achieves the largest third-order nonlinear absorption coefficient of 6155 ± 243 cm GW−1 under 800 nm laser excitation, marking an 8.9-fold increase compared to pristine SnS2 nanosheets. Based on the staggered energy level structure between TMPyP and SnS2, effective enhancement of charge separation/transfer is achieved by leveraging the unique π-conjugated groups of porphyrins, which facilitates the NLO process and improves the NLO performance of films.